Fusible unit



A. C. RQWLEY FUSIBLE UNIT Filed June ll, k3,930

Patented Aug. 29, 1933 FUSIBLE UNIT A Arthur C. Rowley, Philadelphia,

Pa., asslgnor to Globe Automatic Sprinkler Company, Philadelpha,

Pa., a corporation of Pennsylvania Application .nine 11, i930. serial No. 460.51m

1B Claims.

This invention relates to improvements in fusible units and the principal object of the invention is to provide a temperature responsive load-sustaining unitk simple in form and inexpensive to manufacture which shall have greater stability and durability and shall be less subject to deterioration thar. units of like character as previously made.

Another object of the invention is to provide a temperature responsive unit employing as the fusible load-sustaining element a fusible metallic alloy and in which provision is made for protecting the alloy against deteriorating influences.

Still another object of the invention is to provide a unit of the stated character in which provision is made for preventing loss of a major fusible element by evaporation.

In the attached drawing:

Figure 1 is a sectional view illustrating an embodiment of my invention;

Fig. 2 is a section on the line 2 2, Fig. 1;

Fig. 3'is a sectional view illustrating another embodiment of my invention;

Fig. 4 is a sectional view on the line 4 4, Fig. 3;

Fig. 5 is a sectional view on the line 5 5, Fig. 3; and

Figs. 6 and '7 are sectional views illustrating still further embodiments.

With reference to Figs. 1 and 2 of the drawing, 1 is a cylindrical receptacle and 2 is a cylinder which fits more or less neatly within the open end of the receptacle 1 as illustrated. Sufcient clearance is provided between the cylin- .der and the walls of the receptacle to permit escape of a liquid from the interior of the receptacle if pressure is applied forcing the cylinder inwardly. 3 is a cylindrical plug of a suitable fusible alloy or solder, which may be of the type commonly employed in fire control apparatus, this alloy maintaining its rigid form under normal temperature conditions and melting at a predetermined temperature. The element 3 in the present instance constitutes the fusible loadsustaining element of the unit, and in assembly is confined as illustrated in Fig. 1 between the bottom of the receptacle 1 and the inner face of the cylinder 2. It will be noted that the crosssectional area of the plug 3 is suiliciently smaller thanthe cross sectional dimension of thereceptable 1 to permit an appreciable movement of the cylinder 2 under pressure toward the bottom of the receptacle when the plug melts and' loses its normal form, even though none oi' the fused alloy escapes past the plunger. As illustrate'd in Fig. 1, the plug 3 in assembly occupies a central position within the receptacle 1, and the space surrounding the plug 3 is entirely filled with a fusible material which constitutes an envelope entirely surrounding and protecting the fusible element 3, excluding atmosphere and any deteriorating influence from coming into contact with and adversely affecting the element 3. Preferably the fusible protecting material designated in the drawing by the reference numeral 4 constitutes no part of the load-sustaining member and fuses at a point well4 below the fusion point of the alloy of lwhich the plug 3 is constituted.

The enveloping material also is preferably of a character which is of relatively low specific gravity in its fused state. Materials well suited for this purpose are certain chemical salts, such as alphamononitronaphthalene. Preferably the salt is such as to become liquid at a temperature from 5 to 10 below the softening point of the fusible alloy of which the plug 3 is composed. Other compounds suitable for the stated use are ptoluene sulfon dimethylamide, l-nitro-2-naph4 thol, acetyle P-phenetidine, 1.8 dinitronaphthaline, and cyclohexylphthalate 6466 C. These compounds have definite individual meltingA points which vary from 135 to 415 F.

It has been found that this class of compound has a tendency to evaporate even in the solid state, and in order to prevent or reduce this evaporation to a minimum I prefer to employ a suitable sealing means of a character effectively excluding air and moisture and closely confining the compound in the receptacle. By rone method I employ as illustrated in Fig. 1 a sealing layer or film 5 of another of the compounds of somewhat higher melting point which overlles and covers the main body 4 of the protective composition and prevents evaporation of the latter. I may, for example, employ as the main body 4 alphamononitronaphthalene, which fuses at approximately 135; and for the sealing lm I may employ ptoluene sulfon dimethylamide fusing at 175. Other substances may be employed for the sealing film such, for example, as comminuted metallic lead.

That form of device illustrated in Figs. 3, 4 and 5 involves essentially the same structural principle as that described above. In this instance, the cylindrical container 11 is adapted to receive a disk 12 carried at the end of a stem 13. The disk 12, as shown in Fig. 5, is recessed at the edges, as indicated at 12a, and thecontainer 11 is pressed in adjacent the bottom and at opposite sides to form longitudinal ribs 11a, 11a, which project loosely into the recesses 12a to thereby prevent rotation of the flange 12 and of the stem 13 with respect to the container, while permitting relative longitudinal movement of these parts. im

It will be noted further that the recesses 12a are of sufficient depth to provide openings between the bottoms of the recesses and the inner edges of the ribs for a purpose hereinafter set forth. The load-sustaining fusible element in this instance takes the form of a sleeve 14 which surrounds the stem I3 and bears against the` inner` face of the flange 12. A washer 15 slidable on the stem 13 constitutes an abutment for the upper end of the element 14 and also constitutes a cover for the receptacle 11. The space within the receptacle surrounding the element 141s filled with a suitable fusible material such ,as alphamononitronaphthalene whose fusion point is lower than the fusion point of the metallic alloy of which the sleeve 141s composed. The sleeve 14 is thus entirely surrounded and protected by an envelope of iusiblelmaterial except at the ends which are abutted by the flange l2 and the Washer 15 respectively. in this instance evaporation of the fusible salt is prevented by a sealing disc 17 of gold or like inert material capable of conforming to container to create effective This sealing disc is readily in L'on of the unit to permit escape of the fused ilcito tbe container. gurcs l, the sealioV led to units ern ble co'c'lnounds as the sole fusible eletrated named iu.. ments. each instance 2l may indicate body of luttrofnephtliol, constitut the fusible load sustaiong element. ln t, the sealing means consists ci a layer:` of r'ilm of say acetyl lphenetidine; while in Fig. the sealing means consists of a thin disc ci gold or lead. it will be understood that the fusible compounds of the class mentioned are of a character permitting uct-- mission to the receptacle in a fluid state, the com- .pounci solidifyng at s. reduced temperature.

The manner in which these units may be used will be clear to those familiar 'with the art. in tliat form of element shown in Figs. 1 and 2, the sustained load (not shown) is in. the forreoi' a complessive force tending to force the cylinder 2 into the receptacle l, this load being sustained as previously set forth by the element 3. At a predetermined temperature the enveloping fusible substance melts to a liquid or" relatively lov.1 specific vgravity and in the liquid state readily transmits heat from the exterior to the plug 2. When the temperature reaches the melt-iris' point of the plug 3, the load is released by inward movement of the cylinder 2 into the receptacle, which inward movement is permitted by the nieltinfi,T of the plug 3 and the escape of the fused material i between the cylinder and the Walls of the re ceptacle.

1n that form of device shown in Figs. It, Il and 5, the load in the form of a force tendina7 to bring the washer l5 and the flange l2 toward each other is resisted by the fusible sleeve i4 confined therebetween. Melting of the enveloping material i6 and subsequent melting of the sleeve lfl permits such movement and releases the load, the liqueiied enveloping material escaping from the receptacle and through the recesses 12a and permitting the material of the plug to spread outwardly between the washer l5 and the lange 12.

It will be noted that in these devices the fusible element composed of the metallic alloy is placed under compression, as distinct from the prior uses of this material in fusible links and elements in which a material is placed under a tensile force.`

This constitutes a material improvement in the use oi.- this material, sincmunder compression it is materially more stable and less liable to changes than when under tension. Fusible metallic alloys are well suited for use in fusible heat responsive units, but have in the past suffered from a tendency to deteriorate from contact with the atmosphere and other agencies. The present invention provides for complete protection of the metallic alloy against these deteriorating forces.

It will be understood that the invention is not limited to the use of a metallic alloy as the loadsustaining element, and that other substances may be found desirable, particularly where low fusion temperatures are desired. Elements of wax for example may be well suited for the loadsustaining function, but in each instance it is desirable to protect this element from deteriorating influences by means of the fusible envelope as set forth.

I claim:

1. Aifusible unit comprising a fusible load-sustaining element; and a protective envelope therefor of a fusible compound having a fusion point below that of said element and applied directly to vthe latter. n

2. A fusible unit comprising lcad-sustaining element of a fusible metallic alloy; fi pro tesi-ive envelope therefor of non-roet Vfusible: compound of levier fusion peint than alloy and applied dliectly to the said element.

l fusible unit comprising a load-sustaining element of fusible metallic alloy; a protective envelope therefor of non-metallic fusible compound of 'lowerffusion point than said alloy and oi low specific gravity in the fused state applied directly to said element.

e. A fusible unit comprising a load-sustaining element of a fusible metallic alloy; and a protective envelope therefor of alphamononitronaphthalene applied directly to said element. i

5. in a fusible unit, the combination with a fusible load-sustaining element of a volatile composition,

6. In a fusible unit, a container, a fusible loadsustaining compound confined within said conM tainer, ing said, compound therein.

"1. En a fusible unit, a container, a fusible loadsustaining compound confined within said container, and fusible means within the container for t sealing said compound therein.

s. In a fusible unit, a container, e, fusible loadm sustaining compound confined within said con' tainer, and fusible means for sealing the said compound in the container, said sealing means having a higher fusion pointthan said compound and being also confined within the container.

9. .Il fusible unit comprising a fusible load-sustaining element, fusible means preventing accessof air or cti er :duid to said element, a protective cover for said fusible means.

lo. A fusibl unit comprising a fusible metallic load-sustaining element, fusible means preventing; exposure of said element to the atmosphere, and means for preventing exposure to the atmosphere of said fusible means.

1l. A fusible unit comprising a fusible metal lic load-sustaining element, a fusible organic salt protecting said element from exposure to the atmosphere, and means protecting said salt from atmospheric exposure.

l2. A fusible unit comprising a fusible load-sustaining element, means fusible `at a lower tem-- perature than said element for preventing cio posure of said element to the atmosphere, and means having a higher fusion point than the laste named means for preventing exposure of the latter to the atmosphere.

ARTHUR C. ROWLEY.

and in direct Contact with said element y fusible means for preventing evaporation of said composition.

and Within the container for seal- 

